化学腐蚀-冻融综合作用下岩石损伤蠕变特性试验研究

Experimental study of damage and creep property of rock under coupled chemical corrosion and freeze-thaw cycle

为探讨化学腐蚀-冻融综合作用对岩石损伤蠕变特性的影响规律,选取大东山隧道石英岩和石英砂岩开展研究。将岩石试件在不同化学溶液中经历不同冻融循环次数后,采用电镜扫描对岩石表面细观特征进行分析。并开展岩石三轴蠕变试验,分析化学腐蚀-冻融综合作用对岩石瞬时应变、蠕变应变、蠕变速率和长期强度等参数的影响规律。研究结果表明:化学腐蚀-冻融综合作用导致岩石发生损伤,岩石损伤程度随着冻融循环次数的增加而增大,化学腐蚀影响程度由大到小依次为HCl溶液、NaOH溶液和NaCl溶液;岩石各蠕变力学参数随着冻融次数和溶液环境的改变而明显变化。随着化学腐蚀-冻融作用加剧,岩石试件破裂形态有由脆性向延性转变的趋势。冻融循环和化学腐蚀对岩石损伤是相互促进的,双因素耦合作用对岩石损伤和蠕变特性影响均大于单因素的影响。

To study the combined influence of chemical corrosion and the freeze-thaw on the damage and creep characteristics of rock,the quartzite and quartz sandstone of Dadongshan tunnel are adopted to be the test specimens.After being soaked in different chemical solutions and subjected to freeze-thaw cycles with different cycle times,the rock specimens are scanned by the electron microscope to analyze themicroscopic characteristics of rock surface.The triaxial creep tests are carried out to analyze the combined influence of chemical corrosion and freeze-thaw on the parameters of instantaneous strain,creep strain,creep rate and long-term strength of rock.The results show that the rock is damaged under combined influence of chemical corrosion and freeze-thaw cycle,the degree of damage increases with the increase of freeze-thaw cycle time,and the influence of chemical solutions increases by the following orders,HCl solution,NaOH solution and NaCl solution.The creep mechanical parameters of rocks change obviously with the change of freeze-thaw times and solution environment.With the intensification of chemical corrosion and the freeze-thaw cycle,the fracture morphology of rock has a tendency to change from brittleness to ductility.It can be indicated that,in the damage process of rock specimens,the freeze-thaw cycle and chemical corrosion promote each other mutually,since the combined influence of two-factor on rock damage and creep characteristics are greater than the influence of single factor.